Spray containers typically consist of a receptacle for containing the liquid to be sprayed, connected to the upper end of which is a spray cap which includes a single spray orifice of very small diameter, typically 1 mm or less. In use, the liquid is supplied to the spray orifice under pressure and then flows through the orifice. The combination of the high pressure and the small diameter of the spray orifice results in the jet of liquid passing through the spray orifice being discharged from it in spray or atomised form. The pressurisation of the liquid supplied to the spray orifice may be effected in various ways, such as by a liquefied propellant gas contained within the receptacle, a hand-operated pump or by squeezing the wall of the receptacle, which must therefore be of flexible, resilient material. It is with this latter type of spray container that the present invention is concerned. If a pump or a propellant gas is used to generate the necessary pressure, the pressure is relatively high and the liquid is atomised, i.e. broken up into very fine droplets. If the pressure is applied by manually squeezing the wall of the receptacle, the pressure generated is relatively low and the liquid is dispensed in spray form, that is to say in the form of droplets which are significantly larger than those in an atomised spray.
In order to be able to manufacture spray caps it is generally necessary for the spray orifice to be formed in a separate nozzle component and for that component to be subsequently connected to the remainder of the spray cap, whereby conventional spray caps therefore generally include at least two components, which must be manufactured separately and then connected together. This results in a not insignificant manufacturing cost.
When a spray container of the type with which the invention is concerned is operated by squeezing the flexible container, the amount of liquid dispensed tends to be very small and it is generally necessary to squeeze the receptacle a number of times in order to dispense sufficient liquid. In order that the receptacle can return from its squeezed or deformed shape to its original, generally cylindrical, shape under the force of its own resilience it is necessary for a significant volume of air to enter the receptacle and it can generally do this only through the spray orifice. However, the very small diameter of this orifice means that this takes a considerable period of time, particularly as the sub-atmospheric pressure created in the receptacle by the resilience of its wall is very small, whereby the pressure differential which causes atmospheric air to flow into the container is very small also.
The spray issuing from a single spray orifice has a generally conical shape with the majority of the droplets being concentrated in an outer generally circular region and relatively few droplets in the area within the circular region. This means that the coverage of the sprayed liquid on a surface which is to be sprayed is very uneven and in order to obtain something approaching uniform coverage it is necessary to move the spray container from side to side or in a circular motion.